Abstract
Molecular weights of six major polypeptides of infectious bronchitis virus (IBV) are: 1. 75,000; 2. 50,000; 3. 45,000; 4. 35,000; 5. 28,000 or 24,000, and 6. 22,000 dalton. According to the mobility of protein 5 the polypeptide patterns of IBV serotypes fall into two main categories.